Question

Hello guys,

Here are a couple of questions from my Chemistry text book, that I would like to learn how to figure out, some of them already have answers, but I don't get how the answers were found, some of them have some algebra attached and I am bad with algebra so I want to learn how the steps were done, and some of them are ones that I have done a little of but I am stuck in.

Problem #1: the rate is 4.40X10^-3M/s. I do not get how the rate ended up being on the right side and the -1/2 turned into -2 this is algebra, I understand when we get to plug in the rate it is straight forward but I am confused on the first 2 steps, please explain:

Nute At

Problem #2: What is the answer here and how do we figure it out

Problem #3: I understand that since CO had a 0 order, we get Rate=k[NO2]^2. But why is that and what if the order of CO was maybe 1 or 2, would the final rate remain k[NO2]^2??

Final problem: How to solve this and I showed my work where I am stuck on part a, is my part correct so far and if not then what is the correct part for a and how to figure out part b

High rate to whoever answers all, thanks!

Answer 1

1. Here, the coefficient of H⁺ in the reaction on the reactant side (i.e. consuming in the reaction to obtain the product) must be 2.

Hence, in the rate law, rate = -(1/2) ∆[H⁺]/∆t

Here, by cross multiplication, or simply for obtaining ∆[H⁺]/∆t, you have to multiply both sides of the above expression by -2, then you will get ∆[H⁺]/∆t = -2(rate)

2. Here, the order of reaction = 2

Therefore, rate = k[A]²

By substituting the given values, 0.0100 = k(0.100)²

i.e. k = 1

If [A] =0.500 M, then rate = 1*(0.500)², i.e. 0.250 M/s (option D)

3. Given rate expression:

In the above expression, the exponent or power of [CO] term = 0

Therefore, [CO]⁰ = 1 (since (anything)⁰ = 1) and k[NO₂]²*1 = k[NO₂]²

No, if the exponent or power of [CO] term is 1 or 2, then the rate expression must contain k[NO₂]²[CO]¹ (Or) k[NO₂]²[CO]²

4. The rate law you have shown absolutely correct, you have done a wonderful job!!!!!!!!!!!!!!!!!!

Now, coming to part b. consider any one row

Let's consider 1^st row, then you can write as shown below.

0.0035 M/s = k(0.010 M)¹(0.010 M)^0.5

0.0035 M/s = k * 0.010 M * 0.100 M^0.5

0.0035 M/s = k * 0.010 * 0.100 M^1.5

Therefore, k = 3.5 M^-0.5 s^-1

If you take 2^nd or 3^rd or 4^th row, then you will end up with the same value of rate constant. So, don't worry about which row you are considering!

All the best!!!!!!!!!!!!!!!!